Others have commonly deposited tungsten by selective chemical vapor deposition (CVD) to form metal contacts and vias on substrates. Desirable characteristics of tungsten for such applications are well documented in the literature. A common problem others have encountered is the lack of selectivity which exists when tungsten is deposited onto silicon and other materials. Deposition of tungsten on surfaces not desired to be metalized causes manufacturing delay and expense to remove the tungsten from the surface area wrongly metalized. Various methods have been proposed to overcome the stated problem. Typically, selective deposition of tungsten must be accomplished in a clean quartz system with no tungsten or other metal in the fabrication system. Such a clean system is expensive to obtain and maintain and significantly adds to manufacturing overhead. Other known methods and systems which selectively deposit tungsten on substrates are slow and not efficient for mass manufacturing of electronic circuits. Some of the known methods also do not selectively deposit tungsten in very thick layers unless a large amount of time is provided to do so. Some known methods to selectively deposit tungsten also require very specialized and expensive equipment to implement.